This invention relates generally to the field of devices for use in surgery upon tissues of the body. More particularly, the invention relates to an electrosurgical device and methods of treatment of body tissues.
Electrosurgical devices use electrical energy, most commonly radiofrequency (RF) energy, to cut tissue and/or cauterize blood vessels. During use, a voltage gradient is created at the tip of the device, thereby inducing current flow and related heat generation in the tissue. With sufficiently high levels of electrical energy, the heat generated is sufficient to cut the tissue and, advantageously, to cauterize severed blood vessels.
Current electrosurgical devices can cause the temperature of tissue being treated to rise significantly higher than 100xc2x0 C., resulting in tissue desiccation, tissue sticking to the electrodes, tissue perforation, char formation and smoke generation. Peak tissue temperatures as a result of RF treatment of target tissue can be as high as 350xc2x0 C., and such high temperatures may be transmitted to adjacent tissue via thermal diffusion. Undesirable results of such transmission to adjacent tissue include unintended thermal damage to the tissue.
One limitation of current electrosurgical devices arises from size constraints and dimensions. It is difficult to reach or gain access to some tissue and vessels due to anatomy and size constraints. Electrosurgical devices often have movable hinged scissors-like jaws at their tip that must open widely to be placed around the target tissue to be treated. Hinged jaws reduce visibility of the tip and often limit grasping capability of vessels due to force constraints. Further, devices currently used also often have long rigid shafts that cannot bend to maneuver around anatomical xe2x80x9ctightxe2x80x9d spots.
Laparoscopic or minimally-invasive surgery often involves multiple instrument passes through a trocar to achieve the desired tissue effect. Separate instruments are often required for coagulation and for cutting. Separate instruments may also be required to achieve surface hemostasis, such as when there is bleeding from the surface of an organ such as the liver. Multiple instrument passes are undesirable because they (1) waste valuable operating room time, (2) sometimes make it difficult to precisely relocate the target treatment site, (3) increase the risk of infection, and (4) increase the cost by increasing the number of different surgical instruments that are needed to complete the surgical procedure.
Accordingly, there is a need for a surgical device that reduces undesirable effects such as tissue desiccation and resulting tissue damage, char formation, smoke generation, and risk of infection, while at the same time providing improved accessibility to tissues and efficiency.
The invention provides an improved electrosurgical device for coagulating and cutting tissues of the body, utilizing the simultaneous infusion of a conductive solution and application of RF energy. This is accomplished with a device that includes a first electrode positioned on a first arm, and a second electrode positioned on a second arm, wherein at least one of the first arm or the second arm is translationally movable, and at least one of the first electrode or the second electrode is adapted to be coupled to a source of radiofrequency energy. The first arm and the second arm are coaxially arranged. In a preferred embodiment, the device comprises a housing having a proximal and a distal end; a tubular member having a proximal and a distal end, the tubular member extending from the distal end of the housing; a first, translationally movable arm extending from the distal end of the tubular member, the first arm including a first electrode; a second arm extending from the distal end of the tubular member, the second arm including a second electrode and being disposed coaxially with the first arm; at least one solution infusion opening on each electrode; and a solution delivery channel for delivery of a conductive solution to the solution infusion openings, wherein at least one of the first electrode or the second electrode is adapted to be coupled to a source of RF energy.
In a preferred embodiment, the first arm and second arm include at least one groove that surrounds the at least one solution infusion opening. Preferably, the groove(s) include spaced exit slots to allow conductive solution to exit the groove during use (e.g., when pressure is applied to tissues). The grooved arm serves to isolate the metal electrode from direct contact with bodily tissues being treated. Additionally, the grooved configuration provides constant spacing between the electrode and tissue to be treated. Further, the groove assists in preventing tissue pressure against the solution infusion openings during squeezing of the arms of the device, which could inhibit or reduce the flow of electrically conductive fluid locally.
Preferably, the device further comprises a translationally movable cutting mechanism to transect tissue after it has been coagulated. The device can also be used to achieve surface hemostasis with no special adjustments or removal of the instrument from the patient.
In a preferred embodiment, the device further includes a locking mechanism, to selectively lock one or both of the arms of the device in a desired position.
The invention also provides a corresponding method for treating tissues of the body, including, for example, blood vessels. The invention is useful for ligating and dividing a dorsal vein or other blood vessels that are located in deep cavities of the body, as well as for procedures involving polyp removal and laparoscopic tubal ligations.
The invention provides a combination of advantages. For example, the device provides conductive solution, such as saline, at the electrode-tissue interface to limit the peak tissue temperature, preferably to 100xc2x0 C. or less. The provision of saline at the interface prevents tissue desiccation and the various effects of desiccation, such as tissue sticking to the electrodes, perforation of adjacent organs or tissue structures, char formation on electrodes and adjacent tissue, and smoke formation. The saline at the interface preferably maintains peak tissue temperature at or below 100xc2x0 C. by (1) providing coupling of the electrode to the tissue with a wetted contact area that is much larger than that of a dry electrode, thus reducing current density and local RF heating near the electrode-tissue interface, (2) providing a convective cooling effect, such that the flowing liquid saline is heated by the warmer surface of RF-heated tissue, and (3) providing an evaporative cooling effect, such that excess RF power that cannot be conducted or convected away from the target tissue will be used to boil some fraction of the saline provided to the treatment surface.
The invention also provides an instrument that has a lower profile than standard coagulating forceps with hinged jaws. In a preferred embodiment, the device includes a tubular member that has an articulating or bending feature to enable the distal end effector region of the device, including first and second arms, to pass around anatomical features. According to the invention, the device is capable of being made with an outside diameter that is 25 mm or less. Preferably, the device is capable of being made with an outside diameter that is 15 mm or less, more preferably 5 mm or less. As used herein, the outside diameter is the maximum size that the tubular member or first and second arms achieve as a result of device operation.
The invention further provides a multi-purpose instrument that can be used to provide both coagulation and cutting of tissue without having to be removed from the patient""s body. In one embodiment, the instrument is fabricated so that it is capable of sealing and cutting a vessel, as well as causing surface hemostasis on tissue such as bleeding liver.